Examples of so called monolayer crystalline surface (MCS) structures include essentially two-dimensional lattices of carbon (e.g. graphene), nitrogen and boron. When many parallel monolayers are present, such structures constitute a bulk material (as opposed to a film). Layered structures of 1 to 10 layers of essentially coplanar MCS-structures can be termed as few-layered crystalline surface (FCS) structures and they can still be termed films. Bulk or many-layered material containing tens of layers of essentially coplanar FCS-structures, when containing carbon, are termed graphite. FCS-structures can be distinguished from bulk also in that quantum effects are still important when the number of layers is small.
Graphene-based components have wide ranging applications for example in conductive pathways, transistors and sensors. FCS-structures are of great interest due to their unique and useful physical and chemical properties. FCS-structures in, for instance, polymers allow for the creation of flexible and transparent electronic devices.
Ideally, even an individual ribbon of an FCS-structure (containing one or a few monolayers) with a well defined property and in a specific location is sufficient for many applications. An example of such a structure is a Graphene Nano Ribbon (GNR). When these structures are narrow (on the order of a few nanometers wide) or thin (on the order of a few atomic layers thick) they exhibit quantum effects useful for many applications.
The high conductivity of certain FCS-structures, such as graphene, together with the ability to form these structures into 2D structures having extremely high aspect ratios, e.g. into graphene (carbon) nano-ribbons, allow for the production of high performance electronic components. The FCS-structures or the high aspect ratio structures fabricated from them may be utilized, for instance, as the conductive or semi-conductive channel of a transistor or sensor, or as a conductive element in a transparent electrode.
Graphene and carbon nano-ribbon based devices have already been successfully used as gas detectors, transistors, and transparent conductive coatings. Also, they are considered to be strong candidates for the replacement of ITO in transparent electrodes where the high costs of raw materials and production processes, together with performance barriers related to brittleness and coloring, are limiting their commercial lifetime.
For many purposes, the controlled synthesis of FCS-structures wherein the geometry and/or the location of the FCS-structure can be controlled is required. Moreover, FCS-structures already integrated on a substrate can be easier to manipulate, to assemble and to integrate into devices than randomly produced “stand-alone” fragments e.g. in a solution. Moreover, free fragments tend to fold or roll-up, thus reducing or negating many of their useful properties.
To date, manufacturing of FCS-structures in general and of devices based on individual FCS-structures has been too difficult, time-consuming and expensive to be commercially viable. For instance, in the case of graphene, only physical or chemical exfoliation from graphite has been shown to produce carbon MCS-structures (graphene). An example of an exfoliation method is disclosed in “Novoselov K. S., Electric Field Effect in Atomically Thin Carbon Films, Science, Vol. 306, no. 5696, pp. 666-669, 2004”. The drawbacks of such methods include e.g. lack of control of the end-product in terms of both quality and location, and a typically random and fragmented distribution of the MCS sheets on a substrate or in a solution. The problems associated with the prior art methods, the difficulty in producing consistent product, controlling the location of the product on substrates and patterning the product, together lead to complex and expensive manufacturing processes.